UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

Guest
2024-11-22 1:57
 HOME     CONFERENCES     SEARCH            LOGIN     NEW USER     IMAGES   


Conference: Bucharest University Faculty of Physics 2015 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
Chaotic low-frequency fluctuations of the radiation emitted by a semiconductor laser working at currents above the laser threshold


Authors:
Ionut Relu ANDREI(1), Andrei Sorin BALEANU(2), Mihail Lucian PASCU(1,2)


Affiliation:
1) National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania.

2) University of Bucharest, Faculty of Physics, Magurele, Romania.



E-mail
ionut.andrei@inflpr.ro


Keywords:
semiconductor laser, chaos, low-frequency fluctuations,


Abstract:
A complex chaotic behavior can be found in nonlinear dynamics of a semiconductor laser under optical feedback provided by an external reflector. When an external cavity is coupled, the laser system switches to an oscillating state; it follows a chaotic trace. The amplitude of the induced chaotic “noise” seems to be important, depending on the feedback intensity which is between 1% and 10% of laser emission power. One of the most studied issues on the chaotic dynamics is the low-frequency fluctuations (LFF) regime which occurs at laser operation near the lasing threshold and behaves as a cyclic dropout almost to zero of the output light beam intensity. The chaotic behavior of the semiconductor laser emission with external feedback is influenced by laser parameters. Optical feedback intensity, injection current and diode temperature greatly influence the chaotic system evolution. In this paper an extensive analysis of phenomena observed in the laser emission of an external cavity – semiconductor laser (ECSL) system operating in the low-frequency fluctuations regime has been carried out. We present data about the stability of the LFF chaotic dynamics regimes of a semiconductor laser (AlGaInP semiconductor lasers) for different sets of experimental parameters. The injection current was adjusted at values near and over the threshold current corresponding to different set temperatures. LFF regimes were obtained at current values over the threshold current, but only in certain conditions which depend of the intrinsic properties of the active region, respectively at currents where instabilities of mode-hopping type are present in the laser emission dynamics without feedback. The values of parameters for such regimes can only be determined experimentally, but the high temperatures favor the stability of the LFF regime. Also, the amount of feedback intensity must be of the same order of magnitude as at the operation at threshold currents.


Acknowledgement:
This work was supported by the Romanian ANCS/CNDI–UEFISCDI program, projects PN-II-ID-PCE-2011-3-0922 and PN-II-PT-PCCA-2011-3.1-1350, and NUCLEU program, project LAPLAS 3 PN09 39.